Skip to content

Subsurface imaging of the Great Sumatra Fault and Mount Kerinci (Indonesia) using Nodal Ambient Noise Tomography

Elliot Amir Jiwani-Brown1 , Iván Cabrera-Pérez1,  Julien Sfalcin2, Adriano Mazzini3,4, Matteo Lupi1

  • Affiliations: 1Department of Earth Sciences, University of Geneva, Switzerland. 2Invert-geoscience, Switzerland 3Department of Earth Sciences, University of Oslo, Norway. 4Institute for Energy Technology, 2007 Kjeller, Norway

  • Presentation type: Talk [Invited]

  • Presentation time: Tuesday 09:30 - 09:45, Room S160

  • Programme No: 5.1.5

  • Theme 5 > Session 1

Abstract

The Great Sumatra Fault propagates through the central region of West Sumatra, Indonesia. The combination of tectonically driven trans-tensional deformation and lithology promotes the upwelling of magmatic fluids into the intermediate- to upper-crust, forming notable volcanic, hydrothermal, and geothermal subsurface systems. Widespread surface manifestations include hot springs and fumarolic activity occurring within the valley and on the shoulders of the Kerinci volcano.  We used a network of 212-nodal 3-component seismic nodes to produce a high-resolution Nodal Ambient Noise Tomography (NANT) to identify subsurface reservoirs, regions of fluid transfer, and enhancements of permeability. The survey area of 400km2 consisted of a dense distribution of 182 instruments around the populated area of Muara Laboh, and 6-antenna-arrays of 5-seismic-nodes, positioned around the eastern flank of Mount Kerinci. We derived Empirical Green's functions from the cross-correlation of ambient seismic noise from Rayleigh waves, and determined dispersion curves based on the Frequency Time Analysis (FTAN) technique. Group velocity maps were calculated using a nonlinear multi-scale inversion technique and finally we performed a depth using a McMC-transdimensional Bayesian inversion to produce a 3D S-wave velocity model. The inverted S-wave velocity model highlights a number of varying low- and high-velocity domains, often with sharp transitions. We delineate intermediate-velocity transition zones on the shoulders of the low-velocity domains, and suggest that this could represent the boundaries of intrusive bodies containing high-temperature geothermal fluids. One of these zones is located below the current Muara Laboh geothermal field and the others could represent ideal locations of future geothermal energy prospection.